Apparatus for shaping a tubular preform into a hollow body

ABSTRACT

Apparatus for shaping a tubular preform into a hollow body in which an axially directed wall of the preform primarily comprises oriented and/or crystallized plastic material. The tubular preform (10d) is fixed in a circumferential region (13d) in the vicinity of the mouth edge (14d) of the preform between mechanical forming devices (30,40), after which the devices, during continued clamping of the circumferential region, are displaced in the axial direction of the preform relative to a mandrel (50). Thus, the mandrel is displaced into the preform during simultaneous expansion thereof and the material is oriented and/or crystallized. In a preferred embodiment, there is compensation of the stretching forces, which arise in the material when inserting the mandrel, by applying a force to the bottom of the preform by a bottom support (75).

This application is a continuation of Ser. No. 07/334,159 filed on Apr.6, 1989, now abandoned, which is a division of Ser. No. 06/902,456 filedAug. 14, 1986 now issued as U.S. Pat. No. 4,927,591.

FIELD OF THE INVENTION

The present invention relates to a hollow body (e.g. a container) whoseaxially directed wall(s) comprise(s) oriented and/or crystallizedplastic material, in addition to which the invention relates to a methodand an apparatus for reshaping a primarily tubular preform of plasticmaterial into the hollow body by means of mechanical shaping devices.

PRIOR ART

It has been previously known to reshape blanks of thermoplasticsmaterial into a container, where the blank includes portions of axiallyoriented material. The reshaping takes place by means of a blowingprocess, during which the material of the blank is blown against moldwalls whose shape corresponds to the shape of the container beingproduced. Patent publication GB 2.076.731 A describes such a techniquefor the manufacture of a bottle-shaped container.

U.S. Pat. No. 4,381,279 describes a technique where a blank of orientedthermoplastics material is reshaped by a blowing process into acontainer. Also this patent discloses a technique to remold an orientedblank into a container.

U.S. Pat. No. 4,372,908 reveals a technique where a stretched andoriented blank of thermo plastic material is reshaped into a containerby means of one or more mechanical shaping processes. In accordance withthe technique revealed in the patent the circumference of the body ofthe container is reduced during the reshaping of the blank into thecontainer.

There is a considerable need for containers of plastic materialssuitable for high-temperature applications and/or storage of liquidsunder pressure, e.g. storage of soft drinks, beer, etc. High-temperatureapplications means e.g. that the contents of filled and sealedcontainers are pasteurized (60°-70° C.), that the liquid is filleddirectly into the containers at boiling temperature (warm filling) orthat the contents of filled and sealed containers are sterilized (atleast 121° C.).

Further requirements in respect of containers of plastic material arethat it should be possible to manufacture containers in which the bodyof the container and its mouth section have cross-sections independentof each other, e.g. the body has a polygonal cross-section while themouth of the container is circular. The circular shape of the mouth is,as a rule, desirable in order to facilitate sealing of the container.

In order to reduce the unit cost of the containers it is furthernecessary to adapt the distribution of materials in the individualcontainer to estimated mechanical stresses in various parts of thecontainer (mouth, container body and bottom). Additionally, it is alsoimportant that in each region (part) of the container materialdistribution should be as even as possible, since the thinnest and thusthe weakest section of each such region determines the stresses whichthe container is able to withstand. In addition to the materialthickness, the mechanical strength of the containers is naturally alsodetermined by the orientation of the material and/or itscrystallization. It is especially in the case of thermoplastic materialthat the thermal crystallization is of importance.

A further requirement for containers of the kind envisaged here andespecially for a container intended for high-temperature applications isthat the shrinkage which occurs during heating of stretched and orientedthermoplastic material is eliminated or reduced to acceptable values.

In storing liquids under pressure in a container of bottle or can type,it is true in purely physical terms that with an inner pressure in thecontainer its wall material is subjected to a stress that isapproximately twice as large in the circumferential direction than inthe axial direction. In order to improve the strength of the material inthe case of orientable thermoplastic material, the container is moldedin accordance with a known and generally applied technique, by means ofa blowing process, at the same time as the temperature of the materialis adapted to the properties of the material in question, in order tostretch the material during the blowing process and thereby orientatethe same.

The blowing technique possesses the disadvantage that the distributionof material during the molding of the container is not fullycontrollable since, during the expansion of the blank into thecontainer, it is not possible to determine and control exactly where andhow the stretching of the material, and thus its orientation, willproceed. Normally, the stretching begins at a number of starting points,whose positions are determined by the prevailing temperaturedistribution in the material, in addition to stretching forces arisingtherein. The propagation of expansion, and the stretch ratio obtainedare furthermore temperature-dependent, which results in a varyingmaterial thickness of the molded container, i.e. even in a section atright-angles to the axial direction the thickness of the container wallvaries in the circumferential direction. The additional heating of thematerial which takes place when it crystallizes through the stretching,achieves in the material an additional uneven temperature distributionwhich results in an increase in variations in the thickness of the wallin the molded container. Corresponding variations also occur in theaxial direction of the container, i.e. in axial sections through regionsof primarily equally large circumference, alternately thinner andthicker material portions are present. The wall thickness of the blankis thus selected in accordance with known techniques with regard to theaforementioned uncertainty in the stretching and thinning out of thematerial, which implies an overdimensioning of the blank, and thus alsoa surplus of material in the molded container.

In order to attain temperature stability in containers of orientablethermoplastic material, it is known to temperature-stabilize thecontainers in that during the blowing of the containers the containermaterial is allowed to touch hot mold walls against which the materialabuts for a relatively long period (of the order of magnitude of 1-2minutes). This abutment is realized in that after blowing, an inneroverpressure is maintained inside the blown container, whereby the wallmaterial is pressed against the walls of the mold. Long cycle times,however, make this an expensive technique.

SUMMARY OF THE INVENTION

The present invention relates to a technique where all of theaforementioned disadvantages are eliminated. In accordance with theinvention one starts with a preform of orientable and/or crystallizablematerial from which a container is manufactured with high mechanicalstrength and temperature stability and with a considerably improvedmaterial distribution, compared with previously known techniques, inthat this is fully controlled. In accordance with the invention, thetime requirement for the manufacture of each individual container isalso reduced in comparison with that in previous known techniques, inaddition to which the invention allows a simplified construction of theproduction equipment. By means of the invention the quantity of materialin each container is thus reduced, the desired temperature stability isachieved, and costs are reduced in comparison to previously known andused techniques.

In accordance with the invention, a preform of plastic material isreshaped, which has the property of being able to be oriented and/orcrystallized by a mechanical processing, into a container in a number ofconsecutive reshaping processes which, in a preferred embodiment, takeplace in distinctly separate sub-stages. In every such process or stagethe material is stretched (extended) preferably in either the axial orthe circumferential direction of the future container. By stretching thematerial every time to a controlled extent, the material accumulates atotal stretching (extension) and a reduction in thickness equivalent tothat which is required in order to supply the material with the desiredand pre-determined orientation or crystallization and thus the necessarystrength properties. The controlled stretching and the controlledreduction of the material thickness causes the molded container to havethe same material thickness in sections at right-angles to the axis ofthe container, thereby avoiding the variation in thickness, whichcontainers manufactured in accordance with known techniques have inaxial sections through regions of primarily equally large circumference.

In mechanical stretching of the preform or stretching of an intermediatepreform formed from the preform in the circumferential direction, thereare certain difficulties present in achieving a required degree ofstretching in each individual stage of stretching, unless specialmeasures are taken. In accordance with the invention, a primarilyribbon-shaped, circumferential region in the vicinity of the mouth edgeof the preform or the intermediate preform is fixed between mechanicaldevices which displace the preform or the intermediate preform in itsaxial direction across a mandrel during simultaneous expansion of thearticle. Since the material of the article is thus subjected tostretching forces, the tendencies towards folding of the material, whenthe expansion is made in the circumferential direction, are avoided.Especially, the stretching forces are of importance, when reshapingthin-walled articles. It is, in accordance with the invention, alsopossible in many applications to achieve a required increase of thedimensions in the circumferential direction in a single reshaping stage.

In some embodiments, the tractive forces are supplemented by compressiveforces which are applied in the vicinity of the bottom section of thepreform, and which are directed towards the mouth of the preform. Thistechnique is employed when the increase in the dimensions in thecircumferential direction is large.

In accordance with a preferred embodiment of the invention, the preformor the intermediate preform is reshaped into the container in allsub-stages by use of mechanical reshaping devices. The mechanicalstretching (extension or expansion, respectively) takes place in everystage with the material at a specific and controlled temperature whichcan be selected within a wide range. The choice of temperature isdetermined however by the special effect which it is required to achievein the molding stage in question. For materials with a distinct glasstransition temperature, hereinafter abbreviated as TG, e.g. thetemperature of the material in the initial molding stages, is generallylower than TG, while in the concluding stage or stages the temperaturegenerally exceeds TG. In the case of the material, polyethyleneterephthalate, hereinafter abbreviated as PET, the material attains, ina preferred embodiment of the invention, temperatures within the rangeof 70°-180° C., in connection with the concluding shaping stages, whilein the initial shaping stages it generally has a lower temperature.

In certain applications of the invention, e.g. where one intends toobtain a container with a shape which is difficult to achieve by meansof mechanical shaping devices, at least one of the shaping stages, andpreferably the last one, comprises a blow molding stage. In connectionherewith the temperature of the material is, as a rule, set to atemperature close to the maximum temperature at which the material waspreviously shaped mechanically.

BRIEF DESCRIPTION OF THE DRAWING

The invention is described in greater detail in connection with a numberof figures of the drawing, in which:

FIGS. 1-5 show the shaping of a preform into an intermediate preform byextension of the preform in its axial direction when the preform passesthrough a gap that reduces the material thickness,

FIGS. 6-9 show successive stages of the expansion of the preform in itscircumferential direction, and

FIGS. 10-13 show successive stages of the reshaping of the expandedpreform into a container.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a preform 10 with a bottom section 11, a mouth 12, aribbon-shaped, circumferential mouth edge region 13, a mouth edge 14,and an axially directed wall 15, located between the mouth and thebottom section. The central axis of the preform is denoted by referencenumeral 16. The preform is, in FIG. 2, placed in an apparatus fortemperature setting of the preform material. The apparatus includes asleeve 91, a mandrel 92 and a bottom support 93. All these devices areprovided with channels 97 through which a fluid, such as a liquid passesfor individual setting of each device to a certain working temperature.The devices are adjustable to positions where there is formed betweenthem a cavity whose shape substantially corresponds to that of thepreform. A preform which is placed in the cavity is thus enclosed onboth the inside and the outside by the devices and assumes a temperaturewhich in every part of the preform is determined by the temperatures ofthe adjoining devices and the time the preform stays in the cavity.

FIGS. 3 and 4 show a basic apparatus for reduction of the materialthickness of the preform during its simultaneous extension in the axialdirection. The apparatus includes a bottom support 94, a mandrel 95 anda traction device 96 which surrounds the mandrel and is displaced in itsaxial direction by displacement devices (not shown in the Figures).Between the mandrel and the traction device there is defined a slot 90the breadth of which is less than the material thickness of the axiallydirected wall of the preform. The traction devices and/or the mandrel aswell as the bottom support are, as a rule, provided with channels 98through which fluid, such as a liquid passes for regulation of thetemperature of the devices. Depending on the application, heat is eithersupplied or removed by means of the liquid. There is a preform 10a,blocated in the apparatus, and its wall 15a,b, has undergone an axialstretching (extension) and associated crystallization.

FIG. 5 shows an intermediate preform 10b, formed by axial stretching ofpreform 10. The intermediate preform has a bottom section 11b, a mouth12b, a ribbon-shaped mouth edge region 13b, a mouth edge 14b, an axiallydirected wall 15b and a center axis 16, i.e. the parts of theintermediate preform have reference numerals directly equivalent tothose used for the preform 10 described in connection with FIG. 1.

FIGS. 6-9 show a basic embodiment of an apparatus in accordance with theinvention. These Figures show an upper sleeve 30 and a lower sleeve 40provided with channels 42 for temperature setting of the respectivesleeve is assumed to occupy a spatially fixed position, e.g. sleeve 40is affixed to a frame (not shown). The upper sleeve 30 is provided withchannels 33 for flow of a fluid for temperature setting of the sleeve,in addition to which there is disposed inside the sleeve a mandrel 50which by drive means (not shown in the Figure) is displaceable relativeto the upper sleeve in the axial direction of the sleeve. The part 55 ofthe mandrel facing the lower sleeve 40, hereinafter termed the bottomsection, has a shape mainly adapted to the shape of the bottom 11b ofthe intermediate preform 10b, and is in the embodiment shown in FIG. 6thermally insulated from the rest of the mandrel, hereinafter termed theupper section 151 of the mandrel. The bottom section has, in turn, acentral section 56 which is thermally insulated from the outercircumferential portion 57 of the bottom section. In the bottom sectionthere are disposed channels 58,59 for temperature setting of the centralsection of the bottom section and its circumferential portion,respectively. The upper section 151 of the mandrel is also provided withchannels 53 for temperature setting. The upper section of the mandrel,the central section of the bottom section, and its circumferentialportion are thus individually adjustable to required temperatures. Achannel 52 for a pressure medium is disposed in the mandrel and isjoined in the upper section of the mandrel via a connection device 54 toa pressure source 160, and is disposed in the lower section of thebottom section in order to open into the lower limiting surface 150 ofthe bottom section. Inside the lower sleeve 40 there is disposed aninner sleeve 60, displaceable in the axial direction of the sleeve 40 bydrive means (not shown in the Figures), the inner surface 64 of whichhas a shape primarily in correspondence with the outer surface of theintermediate preform. Channels 61 are provided for temperature settingof the inner sleeve.

A bottom support 75 is disposed inside the inner sleeve 60 for axialdisplacement therein by drive means (not shown in the Figures). Incertain embodiments the bottom support is divided into a central section78 and an outer circumferential section 79, thermally insulated from theformer, corresponding to what has been shown in respect of the bottomsection 55 of the mandrel. Channels 76,77 for temperature setting of thebottom support are disposed therein, for which reason the centralsection of the bottom support and its circumferential section are alsoindividually adjustable to required temperatures.

The upper sleeve 30 is provided with an upper stop device 32 whichengages with an upper check (stop) device 99 e.g. adjustably affixed tothe aforementioned frame and placed in a position such that when theupper stop device 32 abuts the upper check device 99 there is formedbetween the upper sleeve 30 and the lower sleeve 40 a columnar cavity21a the breadth of which (the distance between the upper and the lowerdevice in the Figure) exceeds the wall thickness of the circumferentialmouth edge region 13b,c of the intermediate preform 10b,c. In thevicinity of the outer end region of the columnar cavity there is adevice 23 which blocks cavity 21a entirely or partially.

The upper check device 99 can be displaced by the displacement devices(not shown in the Figures) to assume a position where it engages thestop device 32 and a position where the stop device 32 can at leastpartly travel therepast, whereby the upper sleeve 30 can be moved nearerto the lower sleeve 40 (cf. arrows A in FIG. 7).

The inner sleeve 60 is provided with stop devices 62 which in the upperposition of the sleeve abut check (stop) devices 46 in the lower sleeve40. The stop device 62 and the check device 46 establish duringabutment, that the upper limitation surface 63 of the inner sleeve 60,which surface has a shape substantially corresponding to that of thebottom section 55 of the mandrel, forms with said bottom section acolumnar cavity 22 with a breadth somewhat exceeding the wall thicknessin the mouth edge region of the preform. The cavity 22 connects with thecavity 21a so that the two cavities together comprise a linked slot21a-22 the width of which somewhat exceeds the thickness of the mouth ofthe preform edge region. The bottom section 55 of the mandrel has adesign such that its lower limitation surface 150, in a region 51adjacent the upper limitation surface 63 of the inner sleeve 60, has adownwards and outwards directed location with the result that thelimitation surface in this region comprises a guide surface delimitatingthe columnar cavity 22. In the case of a divided bottom section theguide surface is located on the circumferential outer portion 57 of thebottom section.

The upper sleeve 30 is provided with another stop device 31 whichengages a check (stop) device 41 disposed on the lower sleeve 40. Thestop device 31 and the check device 41 have a mutual location such thatwhen the stop device 31 abuts against the check device 41 a cavity 21b(FIG. 9) is formed between the upper sleeve and the lower sleeve, thecavity being of a slotlike shape having a width somewhat less than thewall thickness of the intermediate preform. In FIGS. 6-9, the stopdevice 31 also forms the device 23 which blocks the columnar cavity 21boutwards. Finally, it should be mentioned that in FIGS. 6-9 theintermediate preform has reference characters 10c to 10f, which refer tothe actual reshaping stage of the preform.

FIGS. 10-13 show a reshaped intermediate preform 10g which, comparedwith the intermediate preform 10c in FIG. 6, has an increasedcross-section. In FIG. 11 the ribbon-shaped mouth edge region 13g of thereshaped intermediate preform has been inserted into a slot-shapedrecess 111 in a heating device 110.

FIGS. 12-13 show an outer sleeve 120 having an inner surface 127 whichin the upper section 121 of the sleeve, continuously merges into aninner mouth surface 122 with a reduced circumference. A bottom support130 is supported for displacement within the sleeve by drive means (notshown in the Figures) in the axial direction of the sleeve. In addition,FIGS. 12-13 shown an upper mandrel 140 with a lower, primarilycylindrical section 141 and an upper section 142 with a greatercircumference than the cylindrical section. The lower cylindricalsection of the mandrel is adapted to the mouth surface 122 of the outersleeve such that there is formed between the outer limitation surface145 of the mandrel and inner mouth surface 122, a slot 125 with abreadth somewhat exceeding the material thickness of the mouth edgeregion 13g of the preform. The outer surface 145 of the mandrel has, inthe transition between the lower section 141 and the upper section 142,a shape adapted to the shape of the upper surface 126 of the outersleeve 120 and forms after the transition a surface 146 primarilyparallel to the upper surface of the sleeve in order to form a cavity ora slot 147 between the upper section 142 of the mandrel and the uppersection 121 of the sleeve 120, when the mandrel is in its lowerposition; the cavity 147 forms a continuation of the slot 125, having abreadth that allows the edge region 13g of the reshaped intermediatepreform to be inserted into the cavity. The outer sleeve 120 and themandrel 140 are provided with stop surfaces 123 and 143 respectively,which guarantee the intended distance in the axial direction between thesleeve and the mandrel and thus the intended breadth of the cavity orslot 147. The upper mandrel is, in certain embodiments, also providedwith a channel 144 which, in certain applications, is used in order tosupply a pressure medium to the interior of the preform 10g during itsreshaping.

In a preferred embodiment of the invention, the preform 10 is insertedin apparatus 91-93 for setting of the material of the preform, at leastin its primarily cylindrical section, to a suitable shaping temperature,preferably to a temperature exceeding the glass transition temperatureof the material (cf. FIG. 2). The heated preform is then moved to theapparatus illustrated in FIG. 3 in which the wall thickness of thepreform is reduced during simultaneous axial extension of the wall aswell as orientation and/or crystallization of its material (cf. FIGS. 3and 4) for formation of the intermediate preform 10b, the primarilycylindrical section of which consists of stretched and oriented and/orcrystallized material. FIG. 3 shows the preform during reshaping intothe intermediate preform 10b. In the orientation/crystallization, thematerial passes through the slot 90, by which means the material in apreferred embodiment of the invention obtains an orientation equivalentto that which occurs during material flow. As it moves into the slot,the material generally has a temperature exceeding its TG.

The intermediate preform 10b thus formed is then placed in the reshapingdevice 30,40,50,60,75 illustrated in FIGS. 6-9. The intermediate preformis reshaped into an expanded intermediate preform 10f in the reshapingdevice. In order to allow reshaping, the intermediate preform 10b isfirst placed in a position where it is enclosed by the inner sleeve 60and abuts the bottom support 75. In this position, a temperatureconditioning of the intermediate preform 10b generally takes place, inthat the inner sleeve has a temperature generally somewhat exceeding theglass transition temperature of the material (cf. FIG. 6). If thistemperature conditioning is performed at a temperature which exceeds thetemperature which the material has when passing through the slot 90, theintermediate preforms shrinks axially. In FIG. 6 these two alternativesare denoted in that the intermediate preform has reference characters10b and 10c, respectively, where 10c indicates that the intermediatepreform has shrunk during the temperature conditioning.

The bottom support 75 is subsequently displaced upwards (cf. FIG. 7) atthe same time as the interior 10d of the intermediate preform ispressurized by a pressure medium supplied via the channel 52 from thepressure source 160. In certain applications, the pressure medium isheated in order to maintain or at least contribute towards maintainingthe material of the intermediate preform at the required temperature.The inner sleeve 60 and lower sleeve 40 thus have, relative to themandrel 50 and upper sleeve 30 respectively, positions such that thepreviously described linked slot 21a,22 is formed. FIG. 7 shows anembodiment of the invention where this positional setting is achieved bythe upper stop device 32 when engaging the upper check device 99 and bythe lower stop device 62 when engaging the lower check device 46. Therelative locking between the devices means that during the upwardsmotion of the bottom support, the mouth edge 14b,14c of the intermediatepreform as well as the adjoining mouth edge region 13b,13c are displacedinto the slot during simultaneous increase of the circumference of theintermediate preform in its mouth 12b,12c. This displacement of thebottom support 75 and thus the intermediate preform continues until themouth edge 14d reaches the stop device 31 of the upper sleeve 30. Incertain embodiments, the circumferential outer portion 57 of the bottomsection has an elevated temperature (a temperature exceeding TG) inorder to make the material more adapted to expand in the circumferentialdirection.

The upper check device 99 is subsequently displaced to the positionwhere it can be passed by the stop device 32 (cf. FIG. 8), after whichthe upper sleeve 30 is displaced towards the lower sleeve 40 until thestop device 31 of the upper sleeve abuts against the check device 41 ofthe lower sleeve. In this position, the material portions 13d areclamped in place next to the expanded mouth edge of the intermediatepreform (i.e. equivalent to the ribbon-shaped circumferential mouth edgeregion 13d) between the upper sleeve and the lower sleeve. In theabutment regions for the material portions, the sleeves havetemperatures in excess of TG.

The inner sleeve 60 is subsequently displaced downwards as shown in FIG.8 at the same time as the mandrel 50 which successively expands theintermediate preform in its circumferential direction. The mandrel thushas, at least in the region 51 where it abuts the material of theintermediate preform, a temperature above the TG of the material. As arule, the downwards movements of the mandrel 50 and the inner sleeve 60are synchronized so that the aforementioned slot 22 is maintainedbetween the bottom section of the mandrel and the upper portions of thesleeve. By retaining the material in the mouth region of theintermediate preform in place, the intermediate preform is kept fixedbetween the upper sleeve 30 and the lower sleeve 40 whereby during theexpansion the material in the intermediate preform is also subjected toaxially directed stretching forces through the movement of the mandrel.As a rule, the bottom support 75 is simultaneously allowed to exert anupwardly directed force on the intermediate preform to reduce themagnitude of the stretching forces in the material of the intermediatepreform, when this material is pressed upwards over and expanded by themandrel. Practically, it has been shown that the retention of the edgeportions of the intermediate preform achieves a good result inproduction and a high production capacity. In those applications wherethe retention effect is supplemented by an upwardly directed pressingforce from the bottom support 75, both a further improved result and ashortened cycle time are generally achieved. FIG. 9 shows the shapingdevices after a completed movement and the expanded intermediate preform10f.

Immediately after expansion, the expanded material of the intermediatepreform abuts against the outer surface of the mandrel 50, and as a rulealso the inner surface of the lower sleeve 40. These two surfacespreferably have a temperature exceeding the TG of the material and as arule one considerably exceeding the TG, whereby, the material istemperature-stabilized while retaining the shape that was determined bythe lower sleeve 40 and the mandrel 50. The selected temperature of boththe sleeve and the mandrel and thus the temperature up to whichtemperature stability is achieved is determined by the maximumtemperature at which the product which is being shaped is intended to beused. Thus, for polyethylene terephthalate (PET), containers have beenmanufactured which are temperature-stable up to approximately 160° C. inthat the inner surface had a temperature exceeding 160° C. In certainapplications, the mandrel 50 is also given a corresponding increasedtemperature. As will be evident from FIG. 9 the expanded intermediatepreform 10f has in its mouth section an outwards-facing edge flange 17.In certain applications this is cut off, whereby the expandedintermediate preform 10 g is formed (cf. FIG. 10).

As will be evident from the above description, the bottom section 55 ofthe mandrel 50 also includes both the central bottom section 56 and thecircumferential outer portion 57, which are adjustable to specifictemperatures independently of each other. The bottom support 75 islikewise disposed with similarly separated sections 78, 79. In certainapplications this enables separate heat treatment of the material in thebottom section 11f,11g of the expanded intermediate preform so that whenthe material has a low crystallization it is possible to thermallyincrease the same in order to achieve temperature-stable andshape-stable material portions. Thus, it is possible in accordance withthe invention to obtain in the bottom section of the intermediatepreform annular opaque material portions or disc-like ones.

FIGS. 10-13 illustrate an embodiment of the invention where the expandedintermediate preform 10g after its mouth flange has been cut is reshapedin its mouth section. For this purpose, the ribbon-shapedcircumferential mouth edge region 13g of the intermediate preform isinserted into the slot-shaped recesses 111 in the heating device 110.The material is thus heated to a temperature somewhat exceeding theaforementioned maximum temperature at which the container which is beingmanufactured is intended to be used.

The intermediate preform expanded in this manner is subsequentlyintroduced into the sleeve 120 for reshaping of the mouth 12g of theintermediate preform. By means of relative motion between the bottomsupport 130 and the sleeve 120 the heated material is pressed into theslot 125 between the mandrel 140 and the upper section 121 of the sleeve120 of a reduced diameter, whereby the circumference of the expandedintermediate preform in the mouth section is reduced. By means of asubsequent relative movement between the mandrel 140 and the sleeve 120while simultaneously supporting the intermediate preform by the bottomsupport 130 (with the interior of the intermediate preform beingpressurized if necessary or required) upper edge portions of theintermediate preform are folded outwards and move into the slot 147between the upper section 142 of the mandrel and the upper section 121of the sleeve for the formation of an outwards-facing flange 18. Thus,an embodiment of a hollow body (container) 19 in accordance with theinvention is completed.

In the above description the expressions upper, lower, vertical, etc.have been used, which should, however, be considered solely as a meansof facilitating the description. It is evident that in accordance withthe invention the apparatus can assume arbitrary orientations. It isalso possible, within the scope of the invention, to allow the preform,intermediate preform, and the finished container to have an arbitrarycross-section which may also have a different shape in differentsections of both preform, intermediate preform, and finished container.The reshaping of the mouth section described in the preceding paragraphis also applicable to intermediate preforms of non-circularcross-section. The technique is also applicable to shape non-circularinto circular mouth portions.

The above detailed description has solely referred to a limited numberof embodiments of the invention, but it will be readily understood bythose skilled in the art, that the invention includes a large number ofembodiments within the scope of the following claims.

What is claimed is:
 1. Apparatus for shaping an open mouth of asubstantially tubular preform of deformable plastic material, saidapparatus comprising:means for contacting and inwardly displacing anedge region at an open mouth of a tubular preform around thecircumference of the tubular preform to provide said edge region with areduced diameter compared to the diameter of the tubular preform, andmeans for folding a terminal end portion of said edge region outwardlyto form an outwardly facing flange on said edge region.
 2. Apparatus asclaimed in claim 1 comprising means for heating said edge region priorto the inward displacement thereof.
 3. Apparatus as claimed in claim 1comprising a tubular sleeve surrounding and supporting said preform, abottom support on which said preform rests, said bottom support beingrelatively displaceable in said sleeve, means for relatively displacingsaid tubular sleeve and bottom support to axially displace the preformin the sleeve and apply force from the sleeve to the preform to displacethe edge region inwardly.
 4. Apparatus as claimed in claim 3 comprisinga mandrel inserted into said sleeve to form a circumferential gaptherewith, said sleeve displacing said edge region inwardly to pass insaid gap as the preform is axially displaced in said sleeve. 5.Apparatus as claimed in claim 4 comprising means for relatively movingsaid mandrel and said sleeve to fold said terminal end portionoutwardly.
 6. Apparatus as claimed in claim 1 comprising means forpressurizing the interior of the preform during the inward displacing ofthe edge region.
 7. Apparatus as claimed in claim 3 wherein said tubularsleeve has an inner surface with a diameter against which said preformis engaged so that said mouth of the sleeve is displaced inwardly duringrelative displacement of said sleeve and said bottom support while saidpreform remains engaged with said inner surface of the sleeve. 8.Apparatus for shaping an open mouth of a substantially tubular preformof deformable plastic material having a closed bottom and a tubular wallbetween the closed bottom and the open mouth, said apparatuscomprising:a tubular sleeve in which a tubular preform can be supported,a bottom support relatively displaceable in said sleeve, said bottomsupport supporting a closed bottom of the preform, means for axiallyrelatively displacing said tubular sleeve and said bottom support toaxially displace the preform relative to the sleeve, means on saidsleeve for deforming the preform inwardly at an edge region of an openmouth of the preform circumferentially around the tubular preform toreduce the diameter of said preform when the preform is axiallydisplaced relative to the sleeve, a mandrel insertable into said sleeveto form a circumferential gap therewith, said means on said sleeveholding said edge region of the preform such that said edge regionpasses in said gap as the preform is axially displaced relative to saidsleeve and, means for relatively moving said mandrel and said sleeveaxially with respect to one another to fold a terminal end portion ofsaid edge region outwardly to form an outwardly facing flange on saidedge region.
 9. Apparatus as claimed in claim 8 comprising means forheating the said edge region prior to the inward displacement thereof.10. Apparatus as claimed in claim 8 comprising means for pressurizingthe interior of the preform during the inward displacing of the edgeregion by conveying a pressure fluid through said mandrel into theinterior of the preform.
 11. Apparatus for shaping a substantiallytubular preform of deformable plastic material into a hollow body, thetubular preform having a closed bottom, an open mouth with a flared edgeportion, and a tubular wall of determined diameter between the closedbottom and the flared edge portion, said apparatus comprising,meansincluding mechanical clamping devices for clamping an outer peripheraledge region of said flared edge portion of said tubular preform betweensaid mechanical clamping devices, a mandrel positioned at said openmouth of the tubular preform and having an outer end in spaced relationfrom said closed bottom of the preform so that the preform has aninterior which is hollow and unoccupied, a first outer sleeve in whichsaid mandrel is slidably supported, a second outer sleeve axiallyaligned with said first outer sleeve, said second outer sleeve having aninner diameter, the first outer sleeve having an inner diameter lessthan the inner diameter of said second outer sleeve and means forproviding relative movement of the mandrel, as a first unit, withrespect to said first and second outer sleeves and said mechanicalclamping devices as a second unit, axially of the mandrel and thesleeves, to cause penetration of said mandrel into the hollow interiorof the preform such hat the wall of the preform is circumferentiallyexpanded and travels over said outer end of said mandrel and thenbetween said second outer sleeve and the mandrel to form the hollow bodywith a larger diameter than the diameter of the tubular preform. 12.Apparatus as claimed in claim 11 wherein the plastic material of thepreform has a glass transition temperature (TG), said apparatus furthercomprising means for heating said clamping devices to heat the clampededge portion of the preform to a temperature above said glass transitiontemperature (TG) of the material.
 13. Apparatus as claimed in claim 11comprising means for pressurizing the interior of the preform duringcircumferential expansion thereof.
 14. Apparatus as claimed in claim 13wherein said means for pressurizing the interior of the preformcomprises means for conveying a pressure medium through a channelprovided in the mandrel into the hollow interior of the preform. 15.Apparatus as claimed in claim 11 comprising a bottom support forsupporting the closed bottom of the preform, said bottom support beingsubstantially immovable with respect to said clamping devices. 16.Apparatus as claimed in claim 11 comprising a bottom support forsupporting the closed bottom of the preform, and means for effectingheat exchange between the closed bottom of the preform and the bottomsupport.
 17. Apparatus as claimed in claim 11 wherein said first andsecond outer sleeves have opposed ends and said clamping devices aredisposed at said opposed ends.
 18. Apparatus as claimed in claim 11further comprising an inner sleeve in which a tubular wall of thepreform is supported, said second outer sleeve being slidable on saidinner sleeve, said inner sleeve being movable with said mandrel as saidfirst unit.
 19. Apparatus for shaping a substantially tubular preform ofdeformable plastic material into a hollow body, the tubular preformhaving a closed bottom, an open mouth and a tubular wall between thebottom and the mouth, said apparatus comprising: a mandrel positioned atthe open mouth of the tubular preform, the mandrel having an outerdiameter which is greater than the inner diameter of the tubularpreform, means for clamping said preform at said open mouth includingmechanical clamping devices, means for relatively displacing saidmandrel and said mechanical clamping devices for causing said mandrel tomove into said tubular preform and progressively expand the wall of thepreform circumferentially while said open mouth remains clamped by saidmechanical clamping devices, and a sleeve surrounding and supporting thepreform therewithin, said sleeve being substantially immovable relativeto the mandrel, said sleeve and mandrel forming a gap through which thepreform passes as the mandrel moves into the preform, said gap beingdimensioned so that as the wall of the preform passes through said gap,said wall is stretched on and expanded by said mandrel and is out ofcontact with said sleeve.
 20. Apparatus as claimed in claim 19,comprising a bottom support supporting the closed bottom of the preform,said bottom support being substantially immovable with respect to saidclamping devices.
 21. Apparatus as claimed in claim 19, comprising meansfor pressurizing the interior of the preform between the mandrel and thebottom of the preform during circumferential expansion of the preform.22. Apparatus for shaping a substantially tubular preform of deformableplastic material into a hollow body, the tubular preform having a closedbottom, an open mouth and a tubular wall between the bottom and themouth, said apparatus comprising: a mandrel positioned at the open mouthof the tubular preform, the mandrel having an outer diameter which isgreater than the inner diameter of the tubular preform, means forclamping said preform at said open mouth including mechanical clampingdevices, means for relatively displacing said mandrel and saidmechanical clamping devices for causing said mandrel to move into saidtubular preform and progressively expand the wall of the preformcircumferentially while said open mouth remains clamped by saidmechanical clamping devices, a sleeve surrounding and supporting thepreform therewithin, said sleeve being substantially immovable relativeto the mandrel, said sleeve and mandrel forming a gap through which thepreform passes as the mandrel moves into the preform, said gap beingdimensioned so that as the wall of the preform passes through said gap,said wall is stretched on and expanded by said mandrel and is out ofcontact with said sleeve, and means for shaping the open mouth of thehollow body comprising means for inwardly displacing an edge region atthe open mouth of the hollow body around the circumference of the hollowbody to provide said edge region with a reduced diameter compared to thediameter of the remainder of the hollow body, and means for folding aterminal end portion of said edge region outwardly to form an outwardlyfacing flange of said edge region.
 23. Apparatus as claimed in claim 22,comprising means for heating said edge region prior to the inwarddisplacement thereof.
 24. Apparatus as claimed in claim 22, comprising atubular sleeve surrounding and supporting said preform, a bottom supporton which said preform rests, said bottom support being relativelydisplaceable in said sleeve, means for relatively displacing saidtubular sleeve and bottom support to axially displace the preform in thesleeve and apply force from the sleeve to the preform inwardly todisplace said edge region inwardly.
 25. Apparatus as claimed in claim24, comprising a mandrel inserted into said sleeve to form acircumferential gap therewith, said sleeve displacing said edge regioninwardly to pass in said gap as the preform is axially displaced in saidsleeve.
 26. Apparatus as claimed in claim 25, comprising means forrelatively moving said mandrel and said sleeve to fold said terminal endportion outwardly.
 27. Apparatus as claimed in claim 22, comprisingmeans for pressurizing the interior of the preform during the inwarddisplacing of said edge region.